1. Field of the Invention
The subject invention generally relates to improvements in manhole inserts and, more particularly, mechanisms for removing such inserts.
2. Designs of the Prior Art
Various types and styles of manhole inserts are known in the prior art. These devices are intended to prevent surface water from draining to underground vaults, underground passageways and sewer systems. Basically, the inserts have a dish-shaped body and a flange connected to the edge of the body. The flange engages the manway such that the dish-shaped body is suspended in the manway at times when access through the manway is not required. Fluids are captured in the body of the insert. Examples are shown and described in U.S. Pat. Nos. 3,621,623; 4,305,679; 4,650,365; 5,382,113; and 5,401,114.
Manhole inserts known in the prior art have included various mechanisms for removing the insert when it was desired to have access past the manway. Examples of various handles and straps are shown in U.S. Pat. Nos. 4,919,564 and 5,062,735 and International Publication No. WO 91/16505. However, these structures present various disadvantages and difficulties.
For example, when the insert contains water, it is heavy and relatively difficult to lift by means of handles such as those commonly used in the prior art. Moreover, persons who are required to stoop over to grasp and lift a handle on such an insert are exposed to the risk of painful back injuries and other safety risks. Additionally, if the water in the insert is covered by an oil sheen, the internal structure of the insert is visually obscured and it is often difficult to locate the handle. Moreover, it becomes more awkward and difficult to grasp such handles because they are slippery. Finally, the prior art handle mechanisms did not work well or were even incompatible with J-hooks or similar devices that were intended to provide better mechanical advantage for persons attempting to extract the insert.
Accordingly, there was a need in the prior art for an improved mechanism and method by which to remove manhole inserts from manways.